Posted by: Carla Patrick on July 23, 2002 at 11:37:35

In Reply to: Sewer Gases At Company Posted by: Stacy Raynor on July 07, 2002 at 16:13:13

What is sewer gas?

Answer:
Sewer gas is a complex mixture of that are formed during the decay of household and industrial waste. Highly toxic components of sewer gas include hydrogen sulfide, carbon monoxide, and ammonia.

Sewer gas also contains methane, carbon dioxide, sulfur dioxide, and nitrous oxides. In addition, chlorine bleaches, industrial solvents, and gasoline are frequently present in municipal and privately owned-sewage treatment systems.

How are people exposed to sewer gas? Sewer gas can enter a home through a floor drain or through a blocked gas vent. Prevent sewer gas from entering a home by ensuring that gas traps in floor drains are filled with water and that gas vents are clear of debris. Sanitary and farm workers can be exposed to sewer gas during the cleaning and maintenance of municipal sewers, manure storage tanks, and home septic tanks.

What are the effects of exposure to sewer gas? Sewer gas is a complex mixture of toxic and non-toxic gases that can be present at varying levels depending upon the source of the sewage. The prinicipal risks associated with exposure are:

Explosion and fire. Methane and hydrogen sulfide are flammable and highly explosive at levels above 5% in air.

Hydrogen sulfide poisoning. Exposure to low levels of hydrogen sulfide causes irritation of the eyes and respiratory tract. Other symptoms include nervousness, dizziness, nausea, headache, and drowsiness. This gas smells like rotten eggs; however, exposure to high doses can interfere with the sense of smell making this warning signal unreliable. At extremely high levels, hydrogen sulfide can cause immediate loss of consciousness and death.

Carbon monoxide poisoning. Carbon monoxide is a colorless, odorless gas that can cause suffocation and death at high levels. Exposure to lower levels can produce flu-like symptoms such as headache, nausea, and drowsiness.

Asphyxiation. Sewer gas is heavier than air and contains very little oxygen. Breathing sewer gas even for short periods can result in suffocation and death. Because sewer gas is heavier than air, it can accumulate in basements and is highest at floor level. This poses a high health risk to small children and pets.

How can I avoid being exposed to sewer gas?

Flush floor and sink drains with water to prevent the traps from drying out.
Keep roof vent openings free of debris such as leaves or bird nests.
Never enter a municipal sewer line or manure-storage tank without proper training and equipment.

What should I do if I suspect a problem? If you suspect that sewer gas is entering your home, take immediate action. First, locate the point of entry, such as a basement floor drain or blocked gas vent. By adding water to the floor drain or removing debris from a vent you may be able to prevent sewer gas from entering your home.

If you are unable to identify or correct the problem, you may need to contact a professional plumber or home inspector for assistance. Some local public health departments also offer home inspections.

Symptoms of headache, nausea, dizziness, or drowsiness may indicate exposure to carbon monoxide or hydrogen sulfide. Persons experiencing these symptoms should seek immediate medical care.

At high levels, sewer gas poses a risk of explosion and fire. If you suspect that high concentrations of sewer gas have accumulated in an enclosed space, you should evacuate the area and contact the fire department for assistance. Avoid creating an ignition source such a spark from an electrical appliance, match, or cigarette lighter."